Synchronizing mechanism for telegraph systems



G. A. LOCKE May 25, 1948.

SYNCHRONIZING MECHANISM FOR TELEGRAPH SYSTEMS Filed Feb. 21, 1944 3 Sheets-Sheet 1 \T 3 \2 m: 9 E

May 25, 1948. e. A. LOCKE 2,442,301

SYNCHRONIZING MECHANISM FOR TELEGRAPH SYSTEMS Filed Feb. 21, 1944 3 Sheets-Sheet 2 POLAR/ZED sr/va.

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POLARIZED f L Wi l -l g: lNl/ENTO R N N 6.14. LOCKE ATTOR EV ay 25, 1948. e. 'A. LOCKE 2,442,301

SYNCHRONIZING MECHANISM FOR TELEGRAPH SYSTEMS File d Feb. 21, 1944 3 Sheets-Sheet 3 POLARIZED\ BY A w Y ATTO NEV Patented May 25, 1948 SYNCHRONIZING MECHANISM FOR TELEGRAPH SYSTEMS George A. Locke, Glenwood Landing, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application February 21, 1944, Serial No. 523,262

as Claims. 1

This invention relates to telegraph systems and particularly to systems for synchronizing the operation of telegraph transmitters and receivers.

In start-stop telegraph systems the transmitter impresses on the communication channel groups of significant or selecting impulses, each group being preceded by a start signal which is usual of spacing nature and each group being followed by a stop pulse which is usually of marking nature. The receiving device, such as a teletypewriter printer or reperforator, has a receiving distributor which is held at rest during idle line time, is released for one cycle of operation in response to each start impulse and is stopped after receiving the last significant or selecting impulse, to be restarted in response to the next start pulse. If any start impulse is lost in transmission, which may sometimes occur in wire telegraphy, but is more apt to occur in radio telegraphy, the receiving distributor will not be released for a cycle of operation so as to operate the receiving selector mechanism in timed relation to the significant impulses of the transmitted code, but will be released in response to the first spacing impulse received, which may be one of the significant impulses of the code. This will result in incorrect interpretation of the received code combination by the selector mechanism, and in the case of signals transmitted from a transmitter operating at a steady rate, such as a storage type of transmitter, several code combinations may be incorrectly interpreted before arrestment of the receiving distributor at the end of a code combination and restarting of the distributor under the control of the start impulse preceding the next code combination.

It is an object of the present invention to cause a receiving telegraph device to initiate receiving cycles substantially in unison with the transmitter when start impulses fail to be received from a transmitter normally transmitting start-stop telegraph signals at a steady rate.

When the invention as defined in the foregoing statement of objects is applied to the receiving end of a cipher telegraph system such as that disclosed in Patent No. 2,405,569, granted August 13, 1946, to K. E. Fitch et al., it creates a condition which may make desirable the modification of the apparatus at the transmitting end of the cipher system. According to the disclosure of said patent, signals to be transmitted in cipher are generated by a transmitter as plain text signals and are caused to interact with signals concurrently generated by a storage type of signal generator having in storage a random sequence of codes. The ciphered signals resulting from the interaction of the plain text and ciphering code combination are transmitted to the receiving station where they are caused to interact with signals generated by a storage type of signal generator having the same random sequence of codes in storage. In order for the received signals to be deciphered and plain text signals to be derived therefrom it is necessary that the same code combination interact with the code combination received in cipher that interacted with the plain text code to produce the ciphered code at the transmitting station. Accordingly, it may be desirable to prevent the ciphering signal generator at the transmitting and receiving stations from getting out of step when the apparatus, according to the invention as defined in the foregoing statement of objects, initiates cycles of operation of the distributor upon the cessation of transmission of signals including start pulses.

Accordingly, it is a further object of the present invention to cause the storage type signal generator which generates ciphering signals at the transmitting station to operate, after the gen eration of plain text signals ceases and without disturbing the steady idle condition of marking nature of the communication channel, for the same number of cycles that the receiving distributor is adjusted to operate after the reception of signal combinations including start impulses ceases, so that the storage type ciphering signal generator will be kept in step with the corresponding storage type signal generator at the receiving station.

The invention features electron discharge tubes controlled by adjustable condenser timing circuits for establishing the number of extra distributor cycles that will be initiated at the receiving station and at the transmitting station.

In accordance with the invention there is provided in association with the receiving relay at the receiving station a system of relays controlled by pulsing contacts associated with the receiving distributor of a teletypewriter recorder. Just before the receiving distributor reaches the end of each of its cycles the pulsing contacts are operated to cause the relay system to produce an artificial stop pulse which is applied to the selector magnet of the receiving teletypewriter printer or reperforator. Timing circuits associated with the relay system cause the artificial stop pulse to be terminated just before the beginning of the start impulse should be received from a transmitter transmitting at a uniform rate.

Thereupon other timing circuits associated with the relay system become operative to initiate just after the time when the beginning of the true start pulse should be received an artificial start pulse. If the true start pulse is received, the production of the artificial start pulse will be an idle operation. However, if the true start pulse should not be received the artificial start pulse will be produced and applied to the receiving magnet of the teletypewriter printer or reperforator, thereby releasing the receiving distributor for a cycle of rotation. In this way the receiving distributor will be kept in substantial synchronism with start-stop telegraph signals transmitted at a uniform rate even though start pulses may be lost.

An electron discharge tube controlled by a condenser timing circuit is provided for terminating the production of artificial stop and start pulses. The condenser timing circuit is under the control of the receiving relay and the condenser is discharged each time the relay is operated to spacing, thus recycling the condenser timing circuit repetitiously during the reception of signals. When the transmision of signals ceases and the receiving relay remains in the normal idle or steady marking condition the condenser timing circuit will time out and at the conclusion of the interval for whichit is adjusted the electron discharge tube willfbe operated to cut oh the production of artificial stop and start pulses by the relay circuit. The number of extra cycles of the receiving distributor that will be initiated following the cessation of signal transmission will depend upon the constants of the condenser timing circuit and these constants may be made adjustable. Thus any number of extra cycles of the receiving distributor up t'o a reasonable or desirable limit may be initiated.

In the foregoing' brief description of the synchronizing system at the receiving station reference has been made to the reception of signals transmitted at uniform rate. This is intended to indicate the transmission of signals from a machine transmitter such as a permutation code transmitter controlled by a perforated tape. The synchronizing system at the receiving station is not well adapted tooperation in connection with the reception of signals transmitted by a transmitter which may be operated irregularly, such as a keyboard transmitter, for the reason that the'artificial start pulse mechanism introduces the artificial start pulse a very short interval after failure to receive the true start pulse and the introduction of artificial start-pulses at regular intervals would be wholly inconsistent with operation of the receiving mechanism in response to signals transmittedat irregular intervals.

When the signals received are ciphered signals they may be applied to a reperforator, in which case the signals produced in the tape will represent the ciphered signals in the form in which they were received. As the artificial start pulse mechanism introduces extra cycles of the reperforator upon the cessation of transmission, allmarking codes will be perforated in the tape, one for each of the extra cycles. The tape produced by the reperforator is placed in a transmitterdistributor connected to a deciphering system and the signals generated by this transmitter-distributor are deciphered and the message characters are recorded by a teletypewriter printer connectedto the output of the deciphering mechanism. If that portion of the perforated tape which containstheall-marking code combinations produced during the extra cycles initiated by the artificial start pulses is permitted to run through the transmitter-distributor, the extra code combinations in the tape will cause the deciphering code storage mechanism to advance one step for each code combination perforated in the tape. If the ciphering storage type signal generator at the transmitting station. has been stopped upon the cessation of transmission, the deciphering signal generator at the receiving station will be out of step with it by reason of the extra cycles locally initiated.

The apparatus which may be provided at the transmitting station for preventing the occurrence of an out-of-step condition of the cipher code storage mechanisms at the transmitting and receiving stations comprises a system of relays which become effective when the generation of message signals ceases to initiate continuous operation of the cipher signal generating distributor and at the same time to hold the output of the ciphering system in the steady marking condition. Incident to each cycle of the distributor the next ciphering code in storage is brought into position to perform a ciphering operation but no signals are impressed on the communication channel. Thereis associated with the relay system an electron discharge tube controlled by a condenser timing circuit which begins to time when continuous operationof the ciphering distributor is started. This timing circuitis preferably adjusted to provide a number of cycles of the ciphering distributor equalto the number of extra cycles introduced at the receiver. The condenser timing circuit, upon timing out, operates the electron discharge tube which causes the relay system to arrest the ciphering distributor. Upon the resumption of transmission the ciphering distributor at the transmitter will be in step with the deciphering distributor at the receiver and no adjustments need be made upon. either of these distributors to insure correct decipherment of the message at. the receiving end.

For a complete understanding of the invention I reference may be had to the following detailed description to be interpreted in the light of the accompanying drawings wherein:

Fig. 1 is a diagrammatic view showinga transmitting station including synchronizing mechanism in accordance with the present invention; and

Figs. 2 and 3 when placed end to end with Fig. 3 at the right of Fig. 2 are diagrammatic views showing a receiving station including synchronizing mechanism in accordance with the present invention.

Referring now to the drawings andparticularly to Fig. l, the reference numeral H designates a tape transmitter-distributor which may be of the type shown in Patent 2,055,567, granted September .29, 1936, to E. F. Watson. Perforated tape l2 containing signals to be transmitted by transmitter-distributor H may be prepared in keyboard perforator 13 which may be of the type disclosed in Patent 1,182,179, granted May 9, 1916, to C. L. Krum et al. The disclosures of these patents are incorporated herein by reference as part of the present specification.

The distributor comprises a ring of segments, one of which is the stop segment, another is the start segment and the remainder of which are code segments, a continuous collector ring and a brush arm l4 carrying interconnected brushes which bridge the segmented and continuous rings. Brush arm I4 is driven from motor I6 through clutch ll, gears I8 and I9 and shaft 2|.

Shaft 2| has secured thereto a stop cam 22 which is arrestable by the armature lever 23 of a start magnet 24. The energizing circuit of start magnet 24 includes a battery 20, a manually operable switch 2! and taut tape contact 28.

The code segments of the distributor are connected to contacts which are selectively engageab-le by tape sensing contact tongues which are connected to ground, as is also the stop segment. The collector ring of the distributor is connected by conductor 29 to one terminal of the operating winding of a biased polar sending relay 3|, the other terminal of which is connected to grounded battery 32. With a loop of tape disposed between periorator l3 and transmitter-distributor I!, so that taut tape contacts 28 are closed and with switch 2'! closed, start magnet 24 will be energized and its armature lever will be withdrawn from blocking relation to stop cam 22 so that distributor shaft 2! is released for continuous rotation. The distributor will operate the armature of relay 3! to its marking or spacing contacts in accordance with the stop pulse of marking nature, the start pulse of spacing nature and the several code pulses.

The armature of transmitting relay 3!, which has negative battery on its marking contact and positive battery on its spacing contact, is connected to the tip of plug 33, the sleeve of which is grounded. Plug 33 is insertable into a jack 34 connected to the keying circuit of a radio transmitter indicated symbolically by the rectangle 36. When the armature of relay 3! is on the marking contact and plug 33 is inserted into jack 34, a marking signal is transmitted by radio transmitter 36. When the armature of relay 3! is operated to its spacing contact under the control of transmitter-distributor radio transmitter 36 transmits a spacing signal.

A radio receiver for receiving radio telegraph signals transmitted by radio transmitter 35 is indicated by the reference numeral 20! in Fig. 2. One of the output terminals of radio receiver 20! is connected by conductor 202, springs I and 2 of the right-hand set of springs of a local test key 203 and conductor 204 to one terminal of the operating winding of a biased receiving relay 206. The other terminal of the operating winding of relay 206 is connected through conductor 201, right-hand springs 4 and 5 of key 203 and. conductor 208 to the other terminal of the radio receiver. The armature of relay 206 is held on its marking contact when radio receiver 20! is responding to a marking signal and is operated to the spacing contact when radio receiver 20! responds to a spacing signal. The armature of relay 206 is connected to ground. The marking contact is connected through conductors 2!! and M2, left-hand contact and armature of biased polar relay 2 l 3 and conductor 2 M to the tip spring of a jack ME. A path from conductor 2! to conductor 2!4 in shunt with the left-hand contact and armature of relay 2! 3 is provided by relay 2H when energized, through conductor 2 !8, mid dle upper armature and front contact of relay 2!! and conductor 219. Jack 2H5 is adapted to receive plug 22!, the tip and sleeve terminals of which are connected to selector magnet 30! of: a teletypewriter receiving recorder 352 in Fig. 3 which may be a printing reperforator of the type shown in Patent 2,255,794, granted September 16, 1941, to R. A; Lake. The disclosure of this patent is incorporated herein by reference as part of the present specification. Typing reperforator 302 is provided with keyboard controlled transmitting contacts 303 connected to the tip and sleeve terminals of a plug 222. Plug 222 is insertable into jack 223 which has its sleeve connected to the positive terminal of battery 224. With plug 22! inserted into jack 2I6 and plug 222 inserted into jack 223, a series circuit is established from battery 224 through the sleeve of jack 223 and plug 222, transmitting contacts 303, tip of plug 222 and tip spring of jack 223, sleeve of jack 2 I6 and plug 22!, selector magnet 30!, tip of plug 22! and tip spring of jack 2H5, conductor 2!4, armature and left-hand contact of relay 2l3, conductor 2 2, conductor 2! and armature and marking contact of relay 206 to ground. Jacks 2 l6 and 223 have closed circuit contacts so that battery 224 is always connected through to the marking contact of relay 206 whether either or neither of the plugs 22! and 222 is inserted into the jacks 2H; and 223, respectively, provided the path through the armature and left-hand contact of relay 2l3 or the path through the middle upper armature and front contact of relay2l'! or both paths are closed. With plug 22! inserted into jack 2l6 selector magnet 39! of printing reperforator 302 will be responsive to relay 205 and a message transmitted from tape transmitter-distributor in Fig. 1 will be perforated in the tape 304 and will be printed on the tape so as to be readable therefrom.

The receiving distributor shaft 306 of printing reperiorator 302, which is driven from motor 30'! through gears 303 and 300, is provided with a cam 3!! which is rotated through one revolution for each receiving cycle of the typing reperiorator. Cam 3! I is arranged to momentarily close pulsing contacts 3|2 and the orientation of cam 3!! with respect to the receiving distributor mechanism (not shown) carried by shaft 305 is such that the contacts close and reopen just before the distributor shaft reaches its stop position. Contacts 312 are connected to the tip and sleeve of plug 225 which is insertable into jack 22! and the function of contacts 3!2 is to initiate the operation of synchronizing mechanism now to be described.

The synchronizing mechanism is primarily under the control of relay 2 I! from the standpoint of being in the operative or inoperative condition. ,When relay 2!! is energized the synchronizing mechanism is disabled but when the relay is released the synchronizing mechanism becomes operative. One terminal of the winding of relay 2!! is connected to ground and the other is connected to the armature of a relay 228 and to one of the contact springs of a key 229/ Key 229 is a locking key and when it is operated to engage its contact, battery 23! is connected to relay 2!! to hold the relay energized. Relay 2!! is also energizable through the armature and left-hand contact of relay 228, right-hand and lower lefthand break contacts in series of timing test key 232 to battery 233 which has the same polarity as battery 23!. One terminal of the Winding of relay 2.2.8 is connected to positive battery 234 and the other terminal is connected to the anode of an electron discharge tube which is preferably a vacuum tube. The cathode of tube 236 is connected to ground. The grid of tube 236 is connected through resistor 237 to a condenser charging circuit comprising condensers 232 and 239 connected in parallel and connected to ground through common resistor 24!, and to ground through resistor 242 and battery 243 having its positive terminal connected to resistor 242 and its negative terminal connected to ground. The

'7 Juncti n of resistor 231 and the condenser cha ing circuit i connected through resistor 1244 ha ing a high resistance value and conductor .246 :to the spacing contact of receiving relay 206.

With relay 206 maintained in the steady marking condition during its idle interval ground connection supplied through the armature of relay 26.6 is disconnected from conductor 246 and con- .densers 23B and239are permitted to charge from battery 243. ,As the condensers become charged the, grid of the tube 236 is made more positive with respect .to the cathode until tube 236 will .draw sufiicient current to operate the armature of relay 2% to the left-hand contact. From this it will.:-be apparent that after an idle interval of relay 2616 during which the armature is held on the marking contact, relay 228 will be operated to its left-hand contact and relay 2H will be operated-whether or-not key 229 is closed.

It will now be assumed that key 229 is open .so that battery 231 is disconnected from the winding of relay :2! 1 and that signal transmission from tape transmitter-distributor -l I in Fig. 1 is started. When the armature of relay "266 goes to spacing in response to the start pulse of the first code combination received ground on the armature of relay 2.06 is connected through conductor 246 and resistor 244 to the condenser charging circuit to discharge condensers 238 and 239. The system will be described as if resistor 244 were omitted andthe reason for the provision of that resistor will be set forth later. With ground on the armature of relay 2'06 connect-ed directly to the condenser charging circuit the condensers would discharge very quickly, bringing the potential of the grid of tube 23-6 down to that of the cathode and reducing the current through tube 236 to a value insufiicient to maintain the armature of relay 228 on its left-hand contact. Accordingly, the armature moves away from this contact, interrupting the energizing circuit of relay 2I'1 and releasing that relay. At the outer upper armature and back contact of relay 2H a conductive path is established from conductor 2 I B to the lefthand contact of a biased polar relay 241. At the middle upper armature and front contact the shunt around the left-hand contact and armature of relay 213 is interrupted. At the inner upper armature and back contact of relay H1 a circuit is completed from grounded battery 248 through lamp 249 to ground. Lamp 249 is lighted over this circuit to indicate that the synchronizing mechanism is in operative condition. At the lower armature and back contact of relay 2|1 a short-circuiting path is established around resistor 244. I

As the marking and spacing pulses are received by relay 266 they are repeated to the selector magnet 36! of printing reperforator 362, the receiving distributor of the reperforator, driven by shaft 366 being released for rotation in response to the start pulse, this distributor including the cam 3. During each marking pulse received by relay 266, condensers 238 and 239 begin to change through resistor 242 and each time the armature of relay 266 goes to spacing condensers 238 and 239 are quickly discharged, the resistor 244 being short-circuited by the lower armature of relay 2 l1.

Just before the receiving distributor of printing reperforator 362 reaches its stop position it momentarily closes contacts 312, thus completing a circuit from battery 224 through the sleeve of jack 221, sleeve of plug 226, contacts 3l2, tip of plug 225. tip spring of jack 2-24,conductor 25| and .8 lower or operating windings of biased polar relays .252 and 2-53 to ground. These relays have their biasing windings connected in a circuit from battery 254, biasing windings of biased polar relays 256 and 2l'3, conductor 251, biasing Windings'of relays 252 and 253 to ground. In the absence of current through the operating windings 'of relays 252 and 253 the armature of relay 252 is held on its right-hand contact and the armature of relay 253 is held on its left-hand contact by current through their biasing windings. Upon the completion of the circuit of the operating windings of these relays, the armature of relay 252 is .operated to its left-hand contact and the armature of relay 253 is-operated to its right-hand contact. Relay 252 establishes a holding circuit for itself and for relay 253 from battery 258 of the same polarity as battery 224 through the right-hand contact and armature of a biased polar relay 259. from its left-hand contact disconnects ground from a circuit including conductor 26l, conductor 262 and operating windings of biased polar relays 241 and 263 in series to grounded battery 264. Prior to the operation of relay 253 the \operating-windings of relays 241 and 263 were energized over this circuit to hold the armatures on their left-hand contacts. At the junction of conductors 26! and 262 there is a connection through condenser 266 and resistor 261 to ground. Although ground is disconnected from conductor 26l by the operation ofthe armature of relay 253 away from its left-hand contact, charging current for condenser 266 flows through the operating windings of relays 241 and 263, maintaining the armatures of these relays operated to their left-hand contacts. Upon the movement of the armature of relay 253 into engagement with its right-hand contact a conductive path is established from ground through the noted armature and right-hand contact and conductor 268 to the armatures of relays 241 and 26.3. The left-hand contact of relay 26.3 has no connection but the left-hand contact of relay 241 is connected through the outer upper armature and back contact of relay 2" and .conductor 2|8 to conductor 2|2 which is in the circuit of the selector magnet 3.6I of printing reperforator 362. With the ground connection from the armature of relay 253 extended over this path the selector magnet 30] of printing reperforator 362 is placed in the marking condition independently of the instantaneous condition of relay 266 and this represents the local generation of an artificial stop pulse for the printing reperforator.

As the charging current for condenser 266 decreases the biasing winding of relays 241 and 263 will assume control of these relays and opcrate the armatures to the right-hand contacts. The circuit of the biasing winding of relay 241 includes an adjustable resistor 21! whichis so adjusted that the biasing winding will dominate the armature and move it to the right-hand contact, which has no connection, an instant before the true stop pulse received by relay 206 should be terminated by reception of the beginning of the start pulse, assuming that the distributor of tape transmitteredistributor II is operating-continuously. As the armature of relay 241 leaves its left-hand contact the ground connection supplied by the armature of relay 253 is removed from conductor 2l2, restoring the selector magnet 361 of printing reperforator 362 to control by receiving relay 206. If the start pulse transmitted from tape transmitter-distributor ll.is re.-

Relay 253 upon moving away ceived at the proper time, relay 206 will repeat this pulse to the selector magnet 3M, releasing the receiving distributor of printing reperforator 302 for another cycle of operation.

The circuit of the biasing winding of relay 233 includes an adjustable resistor 272. This resistor is so adjusted that the biasing winding will dominate the armature and move it to the right-hand contact an instant after the true start pulse should have been received by relay 235. With the armature of relay 253 moved to the right-hand contact, a circuit is established from ground on the armature of relay 253 through the righthand contact of that relay, conductor 22%, armature and right-hand contact of relay 233 and op erating windings of relays H3 and 255 to battery 254. Prior to the energization of the operating windings of these relays their armatures are held on their left-hand contacts by the biasing windings in the circuit previously traced includin conductor 257. With the armature of relay 2l3 disengaged from its left-hand contact the conductive path from the marking contact of receiving relay 2% to the selector magnet Bill of printing reperforator 532 is interrupted. This represents the initiation of the artificial start pulse. If the true start pulse has been received, the energizing circuit of selector magnet 32: will have been interrupted by relay 225 before the armature of relay M3 is operated away from its left-hand contact and the latter operation will have no eiiect. If, however, the true start pulse has not been received and the relay 235 has remained in the marking condition beyond the time at which the true start pulse should have been received, the relay 2 l3 will interrupt the energizing circuit of selector magnet 30! and thus intro duce the artificial start condition.

Relay 256, in operating its armature away from the left-hand contact concurrently with the operation of relay 2I3, interrupts a circuit from ground through resistor 213, armature and lefthand contact of relay 255, conductors 253 and 210, and operating winding of relay 259 to battery 258. From the junction of conductors 255 and 210 there is a connection to ground through condenser 2M and resistor 215. Charging current for this condenser flows through the operating winding of relay 259 and maintains the armature of that relay operated to the right-hand contact until the condenser charging current has decreased to such value that the current in the biasing winding of relay 259 dominates the armature. The circuit of the biasing winding of relay 259 includes resistors of such value that the biasing winding assumes control over the armature of the relay and moves the armature away from its right-hand contact to its unconnected left-hand contact about the middle of the true start pulse if received, which aiiords a sufficient interval from the time of operation of relay 253 away from its left-hand contact to insure the release of selector magnet 30! by relay 2l3 ii the true start pulse has not been received. In operating its armature away from the right-hand contact the relay 255 interrupts the holding circuit of the relays 252 and 253 and these relays restore their armatures to the position shown in Fig. 2. Relay 252 further interrupts the holding circuit in preparation for restoration of the armature of relay 259 to its right-hand contact and relay 253 reestablishes the energizing circuit for the operating windings of relays 24'! and 253. Condenser 266 quickly discharges to ground through the left-hand contact and armature of relay 253 and the armatures of relays 2 3i and 233 are immediately operated to their left-hand contacts. Relay 247, restored to the condition shown in Fig. 2, again completes the path from the right-hand contact of relay 253 to conductor 212 in preparation for the production or the next artificial stop pulse. Relay 2-83 interrupts the circuit for the energizing windings or" relays H3 and 253 and the biasing windings of these relays quickly restore the armatures to the left-hand contacts. Relay 253 reconnects the selector magnet 30] to the marking contact of receiving relay 2%, thus terminating the artificial start pulse and restoring the selector magnet to control by the receiving Relay 255 reestablishes the energizing circuit f or the operating winding of relay 259 and condenser 219 quickly discharges to ground, and relay 253 immediately operates its armature to the right-hand contact thus completingtherestoration of the artificial stop and start pulse producing relay system to normal. I

By means of the contacts M2 and the system hereinbeiore described comprising relays 2l3, 241, 252, 253, 255, 259 and 253 an artificial stop pulse is produced in every receiving cycle and an efiort is made to produce an artificial start pulse. If a true start pulse has been received, it is effective to restart the printing reperforator 382 and mask the artificial start pulse. If a true start pulse is lost during transmission and is not received, the relay system introduces the artificial start pulse an instant after the true start pulse should have been received and thus permits the selector mechanism of the printing reperforator to receive and correctly interpret code pulses as if the true start pulse had been received.

At the end or message transmission when transmitter-distributor H in Fig. l is stopped relay 225 will remain in the steady marking condition in the absence of any disturbances on the radio transmission channel which might operate the armature of relay 256 to spacing. Near the end of the cycle of operation of the receiving distributor of printing reperforator 352 in response to the final code combination transmitted, contacts 3l2 will be closed momentarily and will initiate a cycle of operation of relays M3, 241, 252, 253, 253, 2-59 and 263. When relay 24? operates its armature to its right-hand contact, the artificial stop pulse which it seeks to produce will be masked by the steady marking condition of relay 2% in response to the idle condition of marking nature. Thereafter when the armature of relay 253 is operated to the right-hand contact and operates relay 2l3 that relay will disconnect the selector magnet 30! from the marking contact of relay 205, thus introducing the artificial start pulse and releasing the receiving distributor of the printing reperforator 302 for another cycle of operations. Upon the restoration of relay 2i3 to normal as relay 259 operates, the selector magnet 30! is reconnected to the marking contact of relay 2% and the selector mechanism of the printing reperforator interprets the signal received during this cycle as the all marking signal combination and periorates the all marking combination in tape 334. At the end of this cycle contacts 3i2 again are closed momentarily and initiate another cycle of operation of the synchronizing relay system, thus introducing another artificial start pulse and another receiving cycle of a printing reperforator. This sequence of operation continues.

With the armature of relay 206 remaining on its marking contact steadily, condensers 238 and 1- 1 239 gradually charge from battery 243 through resistor 242 because they are afforded no opportunity to be discharged, As these condensers become charged they raise the potential f "the grid of t ube 236 with respec-t to the cathode until the tube draws sufiicient current to operate the armature of relay 2 23 to the left-hand contact. The v l s ine twe n. the fi mtion of relay 20 f5 to themarkirig contact, the operation ofrelay 228to its left-hand contact will depend upon the capacitance of thecondensersystem. The interval maybe reduced by removing one of:the condensers 238 and 239. It may be increased by adding one or gnore condensers in parallel with the condensers 23B and ?39. If desired, a ,single variable condenser of relatively large capacitance or two or, more individually variable condensers connected in parallel may besubstituted for condensers '23 8 and 239 to provide for varying the number of extra artificial rt ulsesa d e QWIfi .Qf pl' v n' forator 30gthat are to be permitted to occur before relay ZZB-QperatQSitS Plmature to -the'lfthand contact. When relay 228 becomes operated by tube 236 it reestablishes the energizing circuit for relay'2 If! which operates. At itso'uter upper armature, ,the relay 2 tl interrupts the artificial stopjpulse circuit. I At its niiddle u'pper armature it reestablishes the shunt around the left-hand contact and armatureofrelay2l3. At its inner upperarmature it extinguishes lamp 24}! 'Fihally at its lower armature it remoyes the shortcircuit'around resistor 2441, Thereafter when rela'y 2I3 is operatedaway fromit left-hand contact by relay 263, an artificial;start-pulsewill not be produced because electromagnet 3! of the printing ;repe rf orator remains connected 'to the marking contact of receiving relay 206 through the middle upper armature and front contact of relay 2 l l establishing a shuiitpath a tmid "the armature and left-hands cz'gntact of relay 2l'3. Thus the printing rperforato'rixiillriiiin at rest. n as Reference is nowmadefto the prpvi sion of 'resisters-2 between messag n eqn a *cflr' 266 and thecopdensercharging circuit comprising condensers-2: 18 and;239, resistor 242and'batt'ery 243. Theresistor Z44 when-not shunted by the armatureof relay 2ll,' wh ich is the condition when the synchronizing system is not'in operation; prevents the substantially insta'intaneous dis charging ofjcondensers 7Z38 ;;and 239 to ground when thei armature; of *relayifl fi goes to spacing, and permitsthe'charge toleal; ofi slowly for the value of resist0rf244'is such-that rela -zcfi must respond to several code combinations during which the'armature of relay 2'05 has operatedto spacing an averagenumber of times before a sufficient nuantltyi-of the charge on condensers 238 -and"239 has leaked oif to-ground to reduce the potential of the gridof tube 235 andtheplate currentinthattubeto avalue at which-the armature of relay -238;will no longer be'rnaintained onits left-hand contact; and will accordingly release relay 2|]. This delayed-interval in the release ofrelay -21! will depend upon the number of spacing -;intervals occurring in the first few codes received-by relay ZllQ The larger the percentage of spacing pulses the more quickly will relayjl'l be released, When it does release, the lower armature short-circuits resistor 244 and thereby provides for substantiallyinstantaneous discharge 0f any charge induced on condensers i238 and 239 during marking intervals, so thatno charge will be gradually accumulated on the con- 7 V 12 denser uuring slgfiall reception, to reduce th rilifiibel bf iitra cycles which'the sync ni in llay system will 'i'ntioduc'alftr'signa-l reception ceases. The principal purpose o'ffresi'st'or '2 is to prevent stra 'di'sturb iiibs'which ma operate the armature of relay-'nfifio s'pacing m'om'etitafily during idle-intervals, when no Signals ar'efbing" feciVd, from il'ist'alil'fia'riebiisly discharging condensers 238 and 239 'and thus efiectingth'e release of relay "2H. R'espon's'e of relay Z06"t'0 such disturbances may 'r'esiilt in interruption 'of the energizing circuit ror eiectroma neteul or the printing reperfoi'ator, so that "the receiving distributor of "the reperrorator is released and contacts M2 are closed 'rh'omentarily near "the end of the cycle. If r'el'ay'zll should'al'so be releasbd, the s ylibhroni'zin'gllay cil'cuitw'ollldbe activated and the predetermined number of extra cycles ofthe printing reperforator would be performed just 'as they are when transmission ceases. B'yp r'ovidin ror the saw discharge of condensers 238 an'd'239, undesired operation of the reperforator in this 'm'anner is prevented. The "fact that 'the synchronizing relay system is not activated assoon as signals begin'to'be recivd'by relay 20ft is not'considereddisadvafitageous 5 because it does be'coi'n'e activated after a few code combinations have been received and it is considered preferable to risk loss of a start pane during these new codes and possible fes'ultinggarbli'ng or a few received signals 'than'it woul be'to'permit' act vation 'of the synchronizing relay-system'and'iritrodiiction of a number of idle operati ns or printing 're'pe'l foiatol '302 in response :tofdisturbar'ices liaving'the effector operating'relafzflfito'spa'cing.

The description "thusra 'has contemplated the transmission of 'plain't'xt 'si'gn'alsfroin transmittr dist'ribiitdr f I in Figalto repeating relay 205 in 'Fig. 2 there being "no ciphering feature involved. Under these-circumstancesthere may or may not beany occasion for reperforating tape at the-receivingjstationand accordingly instead of printingreperiorator fll a teletypewriter printer such as'that disclosedin'Patent 745,633, granted February 4, 1 9'30, 'to 'Sf-Mditbn et al., 01' such as that disclosed in Patent 1,904,164, granted April 18,'1 933, to S.;Morton et'al. maybe provided. Thedisclosures of these pjatents are incorporated herein by'referen'ce'asp'artof thepresent specification. If a iteletypewriter printer having no reperforator ieature is substituted for printing reperiorator-3!l2,--the se1ector magnet of the teletypewritr printer will; be ccnnected to f plug '22 I instead of selector magnetjnl and the keyboard t n m .eent c e w l. be. n cte t Pl 222 instead-of; transmitter c0ntacts'3q3. In the case 1 of the substitution pf either printer there must beaddedto the receiving distributor assembly a ca-irnsimilar to-the cam 3H for operating contacts-3l2. I I i H When messages are to be transmitted incipher, the plain text signalsmust undergo a ciphering operation-before being transmitted. -f'I'he ciphering systemis shown in the-lower; portion of Flg.

-1 to which referenceis now made. Reference numeral 4! fl-designates a tape transmitter-distributor which-may besirnilar to-thetape transmitter-distributor ll and may-receive: perforated tape 42- containing. plain text signals p' erfo'rated by the' keyboard p'rroiatqfla. e v f The actuation-ringer distributor 40" or transother" terminal of which is connected to positive battery 41. Ground is connected to the stop segment and to the transmitting contact tongues of the transmitter-distributor. In Fig. 1 the ground connection is supplied through a relay system which comprises a synchronizing device, but as the present description is concerned immediately only with the generation of ciphering signals, the fact that the ground connection is supplied through a relay system will be disregarded, and the transmitter-distributor All will be considered as if having ground directly on its stop segment and transmitting contact tongues in conformity with transmitter-distributor H. The reason for presenting the description in this way is that it is within the contemplation of the invention to transmit ciphered signals and receive them on reperiorator 382 of Fig. 3 having the synchronizing system of Fig. 2 associated therewith without employing at the transmitting station a synchronizing circuit shown in Fig. 1 and to be described hereinafter.

Relay 46 has negative and positive polarities of battery on its marking-spacing contacts respectively and operates its armature between these contacts under the control of tape transmitter-distributor ii. The armature of relay 45 is connected by conductor 53 to the inner ring of the distributor to of a tape transmitter-distributor 49 which serves as a cipher signal generator and is provided with a perforated tape l having a random sequence of codes perforated therein for ciphering plain text codes generated by the transmitter-distributor Ill. The distributor 50 of the cipher signal generator t9 differs from those hereinbefore, described in that it is provided with a rest segment, in addition to the start and stop segments, to which one terminal of the start magnet 52 is connected, and is also different in that the start, stop and code segments are shorter and there are intervening free or dead segments. When relay is is operated to spacing in response to the start pulse of a code combination generated by tape transmitter-distributor l, a circuit is completed from positive battery on the spacing contact of the relay through conductor 38, continuous ring, bridging brushes and the rest segment of the distributor 59, and winding of start magnet 52 of that distributor to negative battery 53. This causes start magnet 52 to be energized whereby the distributor brush arm is released for one cycle of rotation. These brushes immediately encounter the start segment and complete a circuit from positive battery on the spacing contact of relay 46, through conductor (is, continuous ring, bridging brushes and start segment of the distributor, conductor 55 and then through branching paths, one of which comprises resistor 51 and the other of which comprises the operating winding of a polar relay 53 and resistor 59 in series therewith, the paths rejoining at the junction of resistors 5'! and 59 and continuing through conductor 6| to a potential divider comprising batteries 62 and 63 and resistors S t and 65. With positive polarity supplied over the path just traced to the upper terminal of the operating winding of relay 58, the armature of that relay is operated to spacing. The marking contact of relay 58 has negative polarity and the spacing contact has positive polarity and the armature is connected by conductor 6'! to the tip of a plug 58 which is insertable into jack 34 of radio transmitter 36 for controlling the keying circuit of the transmitter. The sleeve of plug 68 is connected to a potential divider comprising batteries H and 12 and resistors l3 and '14. The armature of relay 58 is also connected through the locking winding of that relay to a potential divider comprising batteries 16 and '11 and resistors wand 19 and the polarities are such that the locking winding seeks to hold the armature on either or" the marking and spacing contacts as the armature engages those contacts, but the locking winding is subordinate to the operating winding so that the operating winding will move the armature from one to the other of the contacts in spite of the opposition of the locking winding.

The distributor 50. rotates in substantial syn-- chronism with the distributor to and by means of its contact tongues, which sense the ciphering code combinations in tape 54, selectively, connects the armature of relay A6 to the upper or lower terminals of the operating winding of relay 58 and the outer ends or the resistors 51 and 59 bridged across the operating winding. There are four possible operating conditions. When the armature of relay 46 engages the marking contact and is connected by the transmitting contacts and segments of the distributor over conductor 56 to the upper terminal of the operating winding of relay 58, the relay is operated to marking. When the armature of relay (56 engages the spacing contact and the armature is connected over the same path, the relay 58 is operated to spacing. When the armature of relay 56 engages the marking contact and the circuit is extended over conductor 54 to the lower terminal of the operating Winding of relay 58, relay 53 is operated to spacing. Finally, when the armature of relay 45 engages the spacing contact and the circuit is extended over conductor E l to the lower termina1 of the operating winding of relay '58, the relay is operated to marking. The summary of these four conditions of operation of relay 58 is that when relay at and cipher signal generator generate like signals, whether marking or spacing, relay 53 is operated to marking and when relay 46 and cipher signal generator is generate unlike signals, either generating a marking signal and the other generating a spacing signal, relay 58 is operated to spacing.

When the brushes of the distributor 5t reach the stop segment, relay 36 will be receiving the stop signal from tape transmitter-distributor GI and will be in the marking condition, applying negative polarity through its marking contact and armature and over conductor 58, the inner ring and stop segment of distributor and conductor 55 to the junction of resistor 51 and the upper terminal of the operating winding of relay 58. The circuit is the same as that traced for the generation of the start pulse but the polarity is reversed so that relay 58 will be operated to marking transmitting the stop pulse.

The ciphered signals are transmitted by radio transmitter 36, are received by radio receiver 2M and are recorded by printing reperforator 322 in' tape 394 in the form of perforations, the syn chronizing mechanism of Fig. 2 hereinbefore described operating to keep printing reperiorator 382 in substantial synchronism with tape transmitter-distributor ii and cipher signal generator 49 in case the start pulses are lost during transmission, and also operating to introduce extra cycles of printing reperforator 36-2 at the conclusion of transmission. The signals appearing as perforations in tape 384 will be in cipher except those resulting from the extra cycles or operation of printing reperforator 392 after Sig- '15 nal reception ceases, which will be unciphered all-marking signal combinations.

In order for the signals perforated in tape 304 to be deciphered, .they' must 'be transmitted by a tape transmitter-distributor :into a deciphering mechanism. Accordingly, as shown in Fig. 3, there is provided at the receiving station, a tape transmitter-distributor 31-6 which may :be similar to the tape'transmitter distributors Isl and M in Fig. 1. It difiers from those transmitter-distributors by being arranged .for the generation of polar signalsand accordingly has both marking and spacing contacts which the tape sensing contact tongues are arranged .to engage selectively under the control of perforations in tape 304. Themarking contacts and-the stop segment are connected through conductor 316, conductor 216, break contacts 25 and :8 on the left-hand side of local test key 203, to negative battery .211. The spacingcontacts and start segment of tape transmitter-distributor 3|6 are connected through conductors F378 and :218 to positive battery 219. The inner ring "of the-distributor'3'lfl of tape transmitter-distributor 3|6 is connected by con'ductors 38| and-281, upper left-hand break contacts of timing test key'232, conductor 282, left-hand contacts 2 and 3 of local test key '293,'conductor 283, right-hand.contacts 8 and 9 of local test key 293and conductor 284 :to the tip spring of jack 236. The sleeve of jack286 isconnectedbyconductor 28.1 and righthand contacts H and I2 of local .test key 203 :to a potential divider comprising batteries .288 .and 289 and resistors '29| and292.

Jack 286 is adapted to receive plug 293 :which is connected by conductors 321 and 322 to the operating winding of .a biased :polar relay 323. Relay 323 has negative and positive polarities, respectively, on its-markingand spacing contacts and its armature is connected by conductor .324 to the inner ring of thedistributorof a cipher signal generator 326 which maybe identical with the cipher signal generator :49 shown in Fig. "1 and which is provided with perforated tape 1321 containing perforated signal codes in a sequence identical with those in the tape Relay 323 and cipher signal generator 326 jointly control a relay 328 in the same manner that relay 46 andcipher signal generator 49 control relay 5 8 injFig. '1. When relay 323 receives a ciphered code combination from tape-transmitter-distributor 316 and jointly with the cipher-signal generator 326 controls relay 328, the cipher signal generator 323 then sensing the same ciphercode combination that produced the ciphered signal, the received signal will be .decipheredand relay 328 will generate the same plain text code that relay "46 received from tape transmitter-distributor 4|. RelayI328 hasnegative and positivepolar- .ities on its marking and spacing contacts, respectively, and its armature is connected-through the winding of a polar relay 329 to a potential divider circuit and also through the locking winding of "relay 328 to a similar potential divider circuit. The armature of relay 3.29 isconnected to .ground and the marking contact is connected to battery through the selector magnet 33| of ateletypewriter printer'332 which maybe of'the type shown in either of the 'Morton'et aL-patents hereinbefore identified. As relay 328 generates the plain text signals, derived fromth'e ciphere'd signals received by relay 323, it will operate relay 329 which in turn controls selectormagnet 33 I and causes teletypewriterprinter "-332 to record the received message i'nplain text.

Following the transmission by tape transmit ten-idistribut'or3 I 6 .of-thelast received code combination .of the message, the all-marking si nal combinations will :be transmitted through relay 323 until the taut :tape mechanism of transmitter-distributor 31:6 interrupts transmission. will zoccur unless an attendant closely watches the passage of tape .304 through transmitter-distributor 3H; and stops the transmitter before transmission of the first of the all-marking signal combinations which were produced durin the extra :cycles oflprinting .reperforator 302. It may not :be feasible to have an attendantsupervis'ing transmitter-distributor 3J6 asgolosely as th'i'sland accordingly it is assumed :that the "3111- marking code combinations will be transmitted. Each of these code combinations :Will be repeated by ,r'elay :323 .to control jrelay 1328 jointly with cipher signal generator 326 and :the distributor of cipher signal generator #326 will operate through one cycle :for each such code combination, tape :32?! being advanced one st p for each cycle. It will .be apparent that the code comhinations repeated by relay 32.8 :to rel y .3 9 and by;relay :329 .to selector magnet ;33;| will not be all marking code combinations because the .ciphering code in tape 32-! will act upon these allmarking codes but under the previouslydescribed method-of cipheringherein employedwherein-two like pulses interact to producea marking pulse and two unlike pulses interact to produce aspacing mulse, any -.code combination which vinteracts with-the all-markingcode combination is regenerated unchanged. Accordin l .the signals ,in ciphering tape 32;! .will be transmitted to selector magnet 3.34 unchanged and the characters recorded -,will ,-be those represented by the codes in ciphering-tapefi-Zl. Since the seguence-of codes in :thisqtape -is assumed to be random, thesecharactors will .convey -no intelligence and there will be no diificultyin identifying the end of thereceived message.

fiincegthe tape 32-! has been advancedone step for each reception by 1'elay,-323\of one of the all grnarking codecombinations it will now-be out Of fs iep-iwith tape 5| in cipher signal generator 4-9 rat :the transmitting station and these two tapes ;must be rephased by agreement between the attendants at the =tw0stations by ,intercorm munication in plain 'textgbefore-further transmission in cipher 'is possible. To obviate the necessity ,of rephasing the cipher tapes a synchronizing system shown-in Fig. 1 hasbeen-provided and will now be 'described.

:The syn hronizing system comp ise rr l y r fl I H12; 1103, EH14 and 19.6. ,FIhe relays 4 04 andllG are included :in the;pla;te :circuits of electron discharge: tubesl El] and |1il 8,;respectively,' and neither of :these 'rrelays :has a locking circuit, so that :wil-l'ibe conductive only when the .grids of their associated :electrcn clischarge' -tubes which atezpreferablyyacuum tubesare sufficiently;positive withrespect :t'oEthe cathjodes to :cause the tubestto'rlrawrenough cur ent to op rate the rey The i l or steadyestate condition or the synchronizing system, which exists when all batteryiconnections:totthersynchronizing -system are complete, rtransmitter-distributor 4| -is idle and has :b'een idle for :an appreciable period of time andithe tauttape contacts J09 or the manually operableswitch ||i| zi-n series therewith areopen, s that irelays ilfl 4,03, ,-04 and I86 are .enenizedxand :relay m2 is released, and the relays aresh'owniin EEig. :1 tinlthi s condition. {The-energizirigcircuit :for relay |0| is traced from bat- 'tery 41 through the operating winding of relay tact and outer upper armature of relay Hi2, conductor iIl, conductor H8 and winding of relay I03 to ground. A holding circuit for relay 503 is also traced from battery I I9 through the front contact and innermost upper armature of relay I03, conductor I 2i, outer lower armature and back contact of relay I02, conductor H3 and Winding of relay I03 to ground. With relay E03 energized ground on the back contacts associated with the middle and outer lower armatures of relay I03 is disconnected from condenser charging circuits which will be specifically identified hereinafter and which are associated with the grids of tubes I01 and I00. The condensers associated with these grids are assumed to be fully charged, so that tubes I01 and I03 are conductive and relays I04 and I06 are operated. ,Relay I33 has prepared a path from the open tauttape contacts I09 through conductors I22, I23, I24, front contact and armature of relay I03, conductors I25 and I21 and winding of relay I32 to ground.

When a message is to be transmitted, keyboard perforator 43 is operated to perforate signals representing the message in tape 42 and as a loop of tape accumulates between perforator as and tape transmitter-distributor 42, taut tape contacts I03 will close. If manually operable switch I II is also closed, battery I28 will be connected over the path just traced to operate relay I32. At its outer upper armature and back contact relay I02 interrupts the energizing circuit for relay I03 traced from battery IIB through the lower armature and front contact of relay IOI, back contact and outer upper armature of relay I02, conductors Ill and H8 through the winding of relay I03 to ground. At its inner upper armature and front contact relay I02 completes its holding circuit from battery I28 through switch III and taut tape contacts I03, conductor I22, front contact and inner upper armature of relay I02, conductors I23 and I21, and Winding of relay I02 to ground. At its outer lower armature the relay I02 interrupts the holding circuit for relay I03 traced from battery II3 through the inner upper armature and front contact of relay I33, conductor I2I, outer lower armature and back contact of relay I02, and conductor H8 and winding of relay I03 to ground. With the energizing and holding circuits both interrupted, the relay I 33 releases. Relay I02 also completes a circuit from battery I3! through its inner lower armature and front contact, conductor I32 and winding of start magnet I33 of tape transmitterdistributor it! to ground. Magnet I33 releases the distributor shaft of tape transmitter-distributor 4! for rotation to transmit the code combination perforated in tape 32.

With relay I03 released a conductive path is prepared from battery I36, the outermost upper armature and back'contact of the relay, conductor I31, upper armature and front contact of relay IOI, conductors I38 and I23 to the inner upper front contact of relay I02. This path parallels the holding path for relay I02 from battery I23 when relay Ii'II is energized. At the middle upper armature and back contact of relay I03 ground is connected over conductors I39 and H3 to the winding of relay IOI, to provide for completion of the circuit of the operating winding of relay 46 when relay I04 shall have been released. At its inner-most lower armature and front contact relay I03 interrupts a path from positive battery I 4| over conductor I42 and conductor 54 to the junction of resistor 59 and the lower terminal of the operating winding of relay 58. The function of this connection which relay I03 interrupts upon being released has been to hold relay 58 in the marking condition when relay 40 operates to spacing under circumstances which will be described later. At the middle and. outermost lower armatures of relay I03 ground becomes connected to the previously mentioned condenser charging circuits, discharging the condensers and grounding the grids of electron discharge tubes It? and I08 to reduce the plate current through those tubes and thereby release relays I04 and I06.

When the brushes of the distributor 40 move off the stop segment the energizing circuit for relay I0] is interrupted and this relay releases. The effect of this is merely to interrupt one of the two holding paths for relay I02 so that the relay does not release. Relay IOI does not become energized during the time that the brushes of the distributor are traversing the code segments because its energizing circuit is opened at the stop segment of the distributor, and the energizing circuit of relay 46 is completed during marking intervals through contacts of the distributor and through conductors I43, H3 and I39, back contact and middle upper armature of relay I03.

Each time that the brushes of the distributor traverse the stop segment relay IOI is energized and then released, but this effects no change in the condition of the other relays of the synchronizing system while switch III or taut tape contacts I09 remain closed. The signals generated by tape transmitter-distributor 4| are ciphered by cipher signal generator 49 and are applied to the radio transmitter through plug 38 and jack 34- in the manner hereinbefore described. The condition of the synchronizing circuit during transmission of signals is that relay IN is energized and released once per cycle of the distributor, relay I02 remains energized and relays I03, I24 and I06 remain released. As long as switch III remains closed and taut tape contacts I09 remain closed, relay I02 will be held energized. If switch III should be opened by manual operation to interrupt transmission, or if keyboard perforator 43 should not be operated with sufficient rapidity to keep up with transmitter-distributor AI, or if the perforation of the message in tape 42 should be completed and the operation of keyboard perforator 43 suspended, the holding circuit of relay I02 will be interrupted, whether by the manual opening of switch III or the opening of taut tape contacts I00 due to reduction of the loop in tape 02 between perforator 43 and trans mitter-distributor M. If interruption of the holding circuit of relay I02 occurs while the brushes are traversing, the stop segment and relay IBI is energized, relay I02 will not bereleased immediately because relay IOI provides an alternate holding path for relay I02 as previously explained. If the distributor brushes are off the stop segment or when they move off the stop segment, relay lei will be released and there will be no holding path for relay I02 which will also release. At the outer upper armature and back of start magnet I33 which releases.

"contact-relay I02 prepares an energizing circuitfor' relay I03-and at the outer lower armature andback contact it prepares a, holding circuit for this relay. At the inner upper armature and front contact relay I02 interrupts its own holding path and at the inner lower armature and front contact it interrupts the energizing circuit This causes the distributor brushes tobe arrested when they reach the. stop segment. As the distributor brushes reach this segment relay I-I- becomes energized and completes the energizing circuit of relay I03 from battery H6 through the front contact and lower armature of relay IOI.

Relay I03 completes its holding circuit from battery-IIO through its innermost upper armature and front contact and the lower outer armature and back contact of relay I02 so that relay Hi3 remains energized. Relay I03 connects positive battery I M over its innermost lower armature and front contact and conductors I42 and I54 to hold the armature of relay 50 on its marking contact. Relay I03 opens the energizing circuit of relay IM and of the operating winding of relay 46 in series therewith by disengagement of the grounded middle upper armature of relay l03 from its back contact. This causes relay 43 to operate to and remain in its spacing condition, completin the energizing circuit for start magnet 52 of cipher signal generator 49 and releasing the distributor 50 for rotation. The brushes of this distributor traverse its segments without changing the condition of relay 58 because the positive polarity supplied through the spacing contact and armature of relay 46 is selectively connected through the distributor to conductor 56, opposing the potential supplied to conductor 54 from battery I4I and reducing to zero the current through the operating winding of relay 58, which is held on its marking contact by the current through the lower or looking winding, or connecting the spacing battery of relay 46 to conductor 54 in parallel with battery IIO. Upon the return of the brushes of the distributor to the rest segment, start magnet 52 is reenergized and the distributor brushes are released for another cycle. Incident to each cycle of the distributor tape 5| is advanced one step but no signals are transmitted by relay 58,

At the time of operation of relay I03, its outer lower armature disconnected ground from the grid of tube I01 and its middle lower armature disconnected ground from the grid of tube I08. The grid of tube I 01 is connected through variable resistor I6! and battery I02 from positive to negative polarities to ground and through condenser I 63 and resistor 64 to ground. With the removal of ground from the grid of tube I01, condenser I63 begins to charge through resistor I6I, raising the potential of the grid with respect to the cathode of the tube. The capacitance of condenser |63 is such and variable resistor I6! is so adjusted that starting from the fully discharged condition of condenser I63 tube I01 will be rendered sufiiciently conductive to operate relay I04 upon completion by the distributor 50 of the same number of cycles that are performed by printing reperforator 302 under the control of the synchronizing relay circuit in Fig. 2 with condensers 238 and'239 starting from the fully discharged condition and relay 200 remaining steadily on its marking contact. When relay I04 is operated it connects ground over conductors H4 and H3; through the winding of relay IOI, conductor 2', stop segment and continuous ring tact actuators.

of distributor 40, and conductor 44 to. the operating winding of relay 46 to reenergizc relay I and to restore relay 45 to the marking condition. With relay 46 restored to the marking condition, start magnet 52 of cipher signal generator 49 will not be energized when the distributor brushes reach the rest segment and accordingly the distributor will be stopped. In this way the tape 5I is advanced a number of steps equal to the number of all-spacingsignal'combinations perforated in tape 334- during the extra cycles of tape transmitter-distributor 302 and when the ciphered signals and the all-marking signal combination perforated in tape 304 have been transmitted by tape transmitter-distributor 3I6 to relay 323 and the signals have been deciphered and the resulting record produced by a teletypewriter printer 332, tape 32'! associated with the cipher signal generator 328 will have been brought into step with tape 5I.

The grid of tube I08 is connected through variable resistor I60 and battery I61 from positive to negative polarities to ground and is also connected through condenser I68 and resistor I69 to ground. The constants of the condenser charging circuit comprising resistor I66 and condenser I68 are such that the conductivity of tube I08 will be raised to a level at which relay I06 will operate a little after relay I04 has been operated by tube I01. Suflicient additional time is afforded for the distributor brushes of cipher signal generator 49 to reach the rest segment and be arrested. Upon the operation of relay I06 a conductive path is traced from ground through winding of relay I02, conductors I21 and I26, armature and front contact of relay I06, conductors I24, I23 and I22 to contacts I09. A path is also traced from conductor I24 through conductor I30 and the upper front contact and armature of relay IOI, conductor I31 to the back contact associated'with the outermost upper armature of relay I03 which is not now engaged by its armature because relay I03 is energized. If the conductive path from battery I28 has been completed through switch I I I and taut tape contacts I00 during the advancementof tape 5I the desired number of teps, the energizing circuit of relay I 02 will be completed and the relay will become energized to restart tape transmitter-distributor M and to release relays I03, I04 and I06. By virtue of the provision'of relay I06 to be operated after relay I04 has operated, the restarting of tape transmitter-distributor M, in the event that a loop of tape 42 is formed of suihcient magnitude to close contacts I09, is delayed until the synchronizing relay circuit has operated through its full cycle. It is thereby assured that tape 5I will be advanced a predetermined number of steps to correspond with the number of extra cycles imparted to printing reperforator 302. In this way, tape transmitter-distributor 4| cannot be restarted while distributor 50 is in any condition but that of rest, and the reception of signals by printing reperforator 302 will not begin while the distributor of the reperforator is in any condition but that of rest.

The local test key 203 in Fig. 2 provides for testing the synchronizing relay circuit by locally generated signals when no signals are being received by radio receiver 20I. This is accomplished by moving the operating handle from the right-hand to the left-hand side to spread the left-hand contact actuators and to release the right-hand con- When this is done the operating winding of receiving relay 206 is disconnected from the conductors 202 and 2.08 over which radio receiver 20! delivers signals, and these conductors are connected together. Conductor284 is disconnected from the continuous ring of the distributor 3|! of tape transmitter-distributor 3H5 in Fig. 3 and is connected instead to negative battery 211. Conductor 28-1 is disconnected from the potential divider comprising batteries 288, and 289 and resistors 29! and 292 and is, connected instead to positive battery 296. These polarities will hold relay 323 in Fig. 3 on its marking contact if plug 293 is connected in jack 286.

Marking and spacing contact conductors 316 and 378 of tape transmitter-distributor 3l6 which extend into Fig. 2 as conductors 21 6 and 218- remain connected to negative and positive batteries 211 and 219, respectively, and conductor 28L from the continuous ring of distributor 3H, connecting through the upper-left-hand break contacts of timing test key 232 and conductor 282, becomes connected to one terminal of the operating winding of relay 206 and the other terminal becomes connected to the potential divider comprising batteries 288 and 289 and resistors 29! and 292. Relay 206 is thus made responsive to signals generated by tape transmitter-distributor 316. A tape containing a test sentence may be placed in transmitter-distributor 3l6 and any time that transmitter-distributor 316 is stopped, as by the opening of its taut tape contacts or by opening of the manually operable switch in the energizing circuit of its start magnet, the synchronizing relay circuit in Fig. 2 will go into operation and will produce extra cycles of printing reperforator 302. During the response of the printing reperforator to the signals contained in the test sentence the orientation range limit'of the selector mechanism of the reperforator may be determined and the optimum orientation adjustment may be made. Also, the condenser charging circuit comprising condensers 238 and 239, resistor 242 and battery 203 may be adjusted to provide the desired number of extra cycles of the printing reperforator after signal transmission from tape transmitter-distributor M6 is terminated.

Timing test key 232 is used for establishing conditions under which variable resistors 21! and 212 in the biasing circuits of relays 241 and 263 may be adjusted to provide the desired delay in the operation of each of these relays. These adjustments are made with the local test key 203 operated to the test condition, whereby tape transmitter-distributor 3l6 is connected 'to the operating winding of receiving relay 2106 but the tape transmitter-distributor is not set in operation. The desired adjustment of relay 24'! is made with the actuator of timing test key 232 operated to the left to open the lower left-hand and upper left-hand break contacts and to close the upper left-hand make contacts. The lower left-hand break contacts open the energizing circuit for the relay 2|! and key 229 should be open so that relay 2|! will be released and the synchronizing relay circuit will be conditioned to operate under the control of contacts 3 l2 in the printing reperforator 302. At the upper left-hand break contacts the operating winding of relay 206 is disconnected from the continuous ring of tape transmitter-distributor H6 and at the upper make contacts it is connected to positive battery 233. This battery provides the same polarity as that which the spacing contacts of tape transmitterdistributor 3 l 6 are arranged to supply and accordingly relay 206 is operated to a steady spacing condition. This causes selector magnet 30l of tape transmitter-distributor 302 to be released and it remains released except for the artificial stop pulse initiated in each cycle by relay 253 and terminated by relay 241.

One of the frequently used signaling speeds is 368 characters per minute and it will be assumed that printing reperforator 302 is geared to operate in response to signals received at this speed. The printing reperforator feeds tape 304 a distance of inch for each cycle of the reperforator and accordingly in one minute will feed 36.8 inches of tape. The driving mechanism of the printing reperforator is arranged to drive this recorder at a substantially higher speed than 368 operations per minute if no stop signals should be received, but the stop signal causes the printing reperforator to be arrested for an interval between each two code combinations received and thus holds the operating speed down to 368 operations per minute. If the stop signals should be shorter than normal length, the printing reperforator will be held'at rest for a shorter interval of time and accordingly it will perform an increased number of operations per minute. As previously stated, relay 241 should be adjusted to operate away from its left-hand contact to terminate the artificial stop impulse an instant before the normal start pulse should be received and the beginning of a, normal start pulse coincides with the end of the true or normal stop pulse. With relay 241 so adjusted the speed of operation of printing reperforator 302 will be higher than the normal signal receiving speed because relay 206 is in the steady-spacing condition and the release of the distributor of printing reperforator 302 is efiected by operation of relay 241, representing termination of the artificial stop pulse.

The preferred practice is to adjust variable resistor Z'll so that in an interval of one minute printing reperforator 302 feeds 37.8 inches of tape, which reprewnts 378 operations per minute. At this speed of operation each cycle of printing reperforator 302 including the stop time occupies approximately .159 second. At the normal receiving speed of 368 operations per minute each operation includin the stop time occupies approximately .163 second. From this it is apparent that relay 24'! has been adjusted to operate away from its left-hand contact and terminate the artificial stop pulse approximately .004 second earlier than the normal termination of the true stop pulse which coincides with the initiation of the start pulse. During the making of this adjustment the artificial start pulse initiated by relay 2l3 upon operation of relay contacts restored to normal, marking battery is reconnected to the operating winding of relay 206 through the upper left-hand break contacts of key 232 so that the relay is held in the steadymarking condition. Thus the only spacing impulses transmitted to printing reperforator 302 will be those representing the artificial start pulse, and the artificial stop pulse Wil1 be masked by the steady-marking condition of relay 206. As previously stated, relay 263 is to be adjusted so that the artificial start pulse is introduced after the time at which the beginning of a normal or true start pulse should be received. The efiect of operation of printing reperforator 302 under the control of the artificial start pulse is to increase the stop time of the distributor in the printing reperforator beyond its normal length and accordingly the printing reperforator will perform less than the normal number of operations per minute. With timing test key operated to the right, the energizing circuit of relay 2H is interrupted at the right-hand break contacts of the key so that the synchronizing relay circuit will operate continuously in repeated cycles under the control of contacts 3|2. However, in order to start printing reperforator 302 it is necessary to operate key 232 to the left momentarily to connect spacing battery to relay 206 so as to transmit a start pulse to selector magnet 30L Key 232 is immediately reoperated to and left in its right-hand position and variable resistor 212 in the biasing circuit of relay 263 is adjusted so that in an interval of one minute printing reperrorator feeds 35.8 inches of tape which represents 358 operations. At this speed each operation or cycle of printing reperforator 302 occupies approximately .l67 second. The diiference between this cyclic time and the normal signal receiving cyclic time of .163 second is .004 second. In this way the artificial start pulse has been timed to occur about the same interval after the time at which a normal or true start pulse should occur as the interval of occurrence of the termination of the artificial stop pulse before the coinciding end of a true stop pulse and beginning of a true start pulse.

As previously set forth, the operation of relay 2-59 occurs about the middle of the true start pulse interval to restore relays 252 and 253, which in turn restore relays 241 and 263, and the latter relay restores relays 2l3 and H6, the former of which ends the artificial start pulse. With the beginning of the artificial start pulse preferably timed to occur .004 second after the time for occurrence of the beginnin of the true start pulse, as described in the preceding paragraph, it will be apparent that the artificial start pulse is considerably shorter than the true start pulse. Since the artificial start pulse is generated locally, and is directly and immediately effective upon the selector magnet 30!, it need be only long enough to cause the selector magnet to release its armature and thereby to release the receiving distributor shaft 306 of the reperforator 302.

With these adjustments made, keys 203 and 232 restored to normal, and the apparatus in condition to receive signals, the synchronizing relay circuit will afford an interval of approximately .008 second throughout which the time of occurrence of the beginning of a true start pulse may vary and if the true start pulse occurs within this interval printing reperforator 302 will be started in response thereto as if the synchronizing relay circuit were not present.

Although a specific embodiment of the invention has been illustrated in the drawings and described in the foregoing specification, it will be understood that the invention is not limited to such specific embodiment but is capable of modification and rearrangement without departing from the spirit of the invention and Within the scope of the appended claims.

What is claimed is:

1. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, and means for locally generating and impressing on said receiving device start and stop impulses in substantial synchronism with the corresponding impulses of received signals.

2. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, means for locally generating and impressing on said receiving device a stop impulse during at least a part of the stop impulse interval of a received signal, and means for locally generating and impressing on said receiving device a start impulse during at least a part of the start impulse interval of a received signal.

3. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, means for localy generating and impressing on said receiving device start and stop impulses in substantial synchronism with the corresponding impulses of received signals, and means operable by said receiving device in each cycle of operation thereof for activating said local start and stop impulse generating means.

4. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, norm-ally inoperative means for locally generating and impressing on said receiving device start and stop impulses, means responsive to the reception of telegraph signals for qualifying said local start and stop impulse generating means to be activated, and means operable by said receiving device in each cycle of operation thereof for activating said local start and stop impulse generating means whereby to cause said means to generate said impulses in substantial synchronism with the cor-responding impulses of received signals.

5. In a. telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, normally inoperative means for locally generating and impressing on said receiving device start and stop impulses, means responsive to the reception of telegraph signals for qualifying said local start and stop impulse generating means to be activated, means for delaying the response of said qualifying means until a plurality of telegraph signals have been received, and means operable by said receiving device in each cycle of operation thereof for activating said local start and stop impulse generating means whereby to cause said means to generate said impulses in substantial synchronism with the corresponding impulses of received signals.

6. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, means for locally generating and impressing on said receiving device start and stop impulses in substantial synchronism with the corresponding impulses of received signals, and means operable a predetermined interval after signal reception ceases and during which interval said receiving device operates under the control of said locally generated start and stop impulses for disabling said local start and stop impulse generating means.

7. In a telegraph system, a start-stopsignal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, means for repeating received signals including tioned storage type signal generator to operate a number of cycles after signal reception ceases, means for causing said first-mentioned storage type signal generator to operate a like number of cycles after operation of said message signal generator ceases, means for suppressing operation of said first-mentioned combining means during said cycles of said first-mentioned storage type signal generator, and means for estopping further operation of said message signal generator until after completion of said cycles of operation of said first-mentioned storage type signal generator.

16. In a telegraph system, a start-stop telegraph signal generator, a storage type signal generator operable conjointly with said start-stop telegraph signal generator to produce ciphered signals, a tape perforating receiver operable in start-stop manner for receiving said ciphered signals, means local to said receiver for generating a predetermined number of start and stop impulses to cause said tape perforating receiver to operate for a like number of cycles when signal reception ceases, and to produce a like number of signal perforations in said tape in addition to those representing said ciphered signals, a tape transmitter controllable by said tape, a storage type signal generator operable conjointly with said tape transmitter in response to all of the signals in said tape for deciphering said ciphered signals, means local to said first-mentioned storage type signal generator for causing alike number of cyclic operations thereof upon cessation of conjoint operation with said start-stop telegraph signal generator whereby to keep said firstmentioned storage type signal generator in phase with said second-mentioned storage type signal generator, and means for suppressing signal transmission during the performance of said like number of cyclic operations.

17. In a telegraph system, a transmitter including a storage type signal generator normally operable in cycles initiated by start impulses and terminated by stop impulses, means for applying start and stop impulses to said generator, a transmitting relay controlled by said generator, means for disabling said start and stop impulse applying means, means responsive to disablement of said start and stop impulse applying means for initiating continuous operation of said generator and for rendering said relay unresponsive to said generator, and means for terminating operation of said generator after a predetermined interval of operation thereof.

18. In a telegraph system, a transmitter including a storage type signal generator having a sequence of codes adapted to be presented in signal generating position in succession, said generator being normal-1y operable in cycles initiated by start impulses and terminated by stop impulses, means for applying start and stop impulses to said generator, a transmitting relay controlled by said generator, means for disabling said start and stop impulse applying means, means responsive to disablement of said start and stop impulse applying means for initiating continuous operation of said generator whereby to cause a plurality of said stored codes to be advanced past said signal generatin position and for rendering said relay unresponsive to said generator, and means for terminating operation of said generator after a predetermined interval.

19. In a telegraph system, a transmitter including a storage type signal generator normally operable in cycles initiated by start impulses and terminated by stop impulses, means for applying start and stop impulses to said generator, a trans;

mitting relay controlled by'said generator, means for disabling said start and stop impulse'apply ing means, means responsive to disablement or said start and stop impulse applying means for initiating continuous operation of "said generator and for rendering said relay unresponsive to said generator, timing means activated concomitantly with initiation of continuous operation of-said generator, and means controlled by said timing means upon timing a predetermined interval for stopping said generator; r

20. In a telegraph system, a transmitter in-@ cluding a storage type signalgenerator normally operable in cycles initiated by start impulses'and terminated by sto'pimpulses, means for applying start and sto impulses'to said generator, a transmitting relay controlled by said generator, means for disabling said start and stopimpulse applying means, means responsive to disablement of said start and stop impulse applying means for initiating continuous operation of said'generator and for rendering said relay unresponsive to said generator, meansfor'stop'ping said gen erat'or after a predeterminedinterval of operation thereof, and meansfor estopping reactivation of said start and stop'impulse applying means untilafter the stopping of said'generator. "i

21. In a telegraph system, a start -stop telegraph transmitter, a startestop receiver, ajcom- *munication channel over which said receiver may receive start-stop signals from said transmitter, means local to said receiver .for generatingrand impressing start and stop impulses on'said re,-" ceiver, and means for causing said last-mentioned means to generate said impulses in substantial synchronism with the start and stop impulses of receivedsignals.

22. In a telegraph system, a transmitter for transmitting code combinations each comprising a start impulse, a plurality of significant impulses and a stop impulse, a start-stop receiver for receiving said code combinations; means local to said receiver for generating and impressing start and stop impulses on said receiver, and means for causing said last-mentionedmeans togenerate said impulses in the interval between the last significant impulse of each received code combination andthe first significant impulse of the succeeding code combination.

23. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses, means responsive to start impulses of received signals for starting said device, and means for locally generating and impressing start impulses on said starting means in substantial synchronism with the corresponding impulses of received signals. 7

2a. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses, means operable in response to received start impulses for starting said device, and means for operating said startingmeans in the absence of received start impulses.

25. In a telegraph system, a start-stopsignal receiving device operable in cycles initiated by start impulses, means responsive to start impulses of received signals for starting said device, and means for locally generating and impressing a start impulse on said starting means during at least a part of ,the start impulse interval of re ceived signals.

26, In a telegraph system, a start-stop signal receiving ;devic e operable in cycles initiated by l 25 thestart and stop impulses thereof to said receivingflevice, normally disabled means for callygenerating and impressing on said receiving device start and stopimpulses, means responsive to said repeating means for qualifying said local start and -stop pulse generating meansto be actiyated, means operable by said receiving devicein each cycle of operation thereof for activating said local start and stop pulse generating means, means for disabling said local start and stop. Pulse generatingmeans, and timing means for operating said disabling means a predetermined interval after signal reception by said repeating means ceases.

8. In ,a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, means for locally generating and impressing on said'receiving device start and stop impulses, means for impressing received telegraph signals includingthe start and stop impulses thereof on said receiving device, andmeans for limiting to a predetermined number the cycles of said receiving device in responseexclusively to said locally generated start and stop impulses.

9. In a telegraph system, a start-stop signal receiving-device. operable in cycles initiated by start impulses and terminated by stop impulses, means-for impressing received telegraph signals includingv the start and stop impulses thereof on-said receivingidevice, and means for locally generatingand impressing on said receiving devicesstart impulses beginning and ending within thenintervals of correctly received full length start impulses and stopimpulses beginning and ending within the interval of correctlyreceived full length stop impulses whereby correctly received full length start and stop impulses mask the corresponding locally generated impulses.

10.- In a telegraph system, a start-stop signal receivingdevice operable in cycles initiated by start impulses and terminated by stop impulses, means for impressing received telegraph signals including the start and stop impulses thereof on said receivingdevice, means for locally generating andimpressing stop impulses on said receiving device, means for terminating said locally generated stop-impulses in advance of the time for occurrence of the coinciding termination of the stop impulse and initiation of the start impulse of correctly received normal length signals, and means for locally generating and impressing start impulses on said receiving device after-the-time ior occurrence of the coinciding termination oi-the. stop impulse and initiation of the start impulse of correctly received normal length signals whereby said receiving device is controllable primarily by received stop and start impulses and secondarily by locally generated stop and start impulses.

11. Ina telegraph system, a start-stop transmitter, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, means for locally generating start and stop impulses to cause said receiving'device to operate a predetermined number of cycles after signal reception ceases, means for causing said transmitter to operate a like number of "cycles after message transmission ceases, and means for suppressing transmission of any impulses by said transmitter during said cycles.

12; In a telegraph system, a start-stop transmitter, a start-stop signal receiving device .01:- erable-incycles initiated by start impulses a'nd terminated by stop'impulses, means local to said receiving device for generating start and stop impulses tocausesaid receivingdevice to oper-' ate a-predetermined number of I cycles after. signal reception ceases, means for causing said trans- 5 mitter to operate a like numberof cycles after pressing transmission of any impulses by said transmitter during said cycles, and meansvarying said number of cycles of said receiving device and of'said transmitter.

mitter, a start-stopsignal receiving device 01 3 able in-cycles initiated by start impulses and tarminated by stop impulses, means local to said receiving device for generating start and stop inrpulses. to cause said receiving device to operate a predetermined number of cycles after signal receptlor ceases, means for causing said transmitter I to operatea like number of cycles after messa e transmission ceases, means for suppressing transmission of any impulses by saidtransmitter during said cycles, and meansfor precluding resump tion of message transmission until after completion of said predetermined number of cycles by saidtransmitter.

14. In a telegraph system, astart-stop message signal generator, a start-stop storage type of signal generator having a sequence of non messa e,

codes in storage, a communication channel, means for interactively combining signals generated by said message signal generator and signals gener-; ated by said storage type signal generator and for impressingthe resulting signals on said channel, means operable in cycles initiated by start impulses and. terminated by stop impulses for receiving said signals from saidchannel, a storage type of signal generator having a sequence of codes in storageidentical with, said first-men: tiond sequence of codes, means for causing the signals received by said receiving means to be said second-mentioned storage type signal generator whereby to derive the original message signals, means local to said receiving means for generating start and stop impulses to cause said receiving means and said second-mentioned storagetype signal generator to operate a number of signals generated by said storage type signal generator and for impressing the resulting signals on said channel, means operable in cycles initiated by startimpulses .and terminated by stop impulses for receiving said signals from said channel, a storage type of signal generator having ,a

sequence of codes in storage identical with said.

first-mentionedsequence of codes, means for causing the. signals. received by. said receiving message signals, meanslocal to said receivin means for generating start and stop impulses .to

cause said receiving means and said second-men- 13. In a telegraph system, a start-stoptransinteractively combined withsignals generatedby generated. by said messagesignal generatorand means to be interactively combinedwith signals, generated bysaid second-mentioned storage type. signal generator Wherebyto. derivethe original start impulses, means responsive to start impulses of received signals for starting said device, and means for locally generating and impressing start impulses on said startin means in substantial synchronism with corresponding impulses of received signals and of sufiicient duration to effect the operation of said starting means.

27. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses, means for locally generating and impressing on said receiving device start impulses in substantial synchronism with the corresponding impulses of received signals, and means for disabling said start impulse generating means a predetermined interval after cessation of signal reception,

28. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses, means for locally generating and impressing on said receiving device start impulses in substantial synchronism with the corresponding impulses of received signals, and means for disabling said start impulse generating means upon the generation thereby of a predetermined number of said start impulses after cessation of signal reception.

29. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses received incidental to accompanying code impulses, start means for initiating cycles of said receiving device in the absence of received start impulses, and means for limiting the number of consecutive operations of said start means during a period of time in which no impulses are received.

30. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses, a signal responsive relay for repeating received signals including start impulses to said receiving device, and a relay for locally generating and impressing on said receiving device start impulses in substantial synchronism with the corresponding impulses of received signals.

31. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses, a signal responsive relay for repeating received signals including start impulses to said receiving device, a relay for locally generating and impressing the start impulses on said receiving device, and means for operating said last-mentioned relay in substantial synchronism with the start impulses of received signals.

32. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, means for locally generating and impressing on said receiving device start and stop impulses, and timing means for causing said start and stop impulse generating means to be activated in substantial synchronism with the corresponding impulses of received signals.

33. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by step impulses, means for locally generating and impressing on said receiving device start and stop impulses, and means operable a predetermined interval after the beginning of any received or locally generated start impulse for activating said start and stop impulse generating means.

34. In a telegraph system, a start-stop signal receiving device operable in cycles initiated by start impulses and terminated by stop impulses, means for locally generating and impressing on said receiving device start and stop impulses, means operable a predetermined interval after the beginning of any received or locally generated start impulse for activating said start and stop impulse generating means, and means operable after a predetermined number of successive cycles of said receiving device initiated exclusively by said local start impulse generating means for disabling said activating means.

35. In a telegraph signal repeating device, an incoming signaling path, an outgoing signaling path, a receiving relay associated with said incoming path and adapted to cause received signals to be impressed on said outgoing path, and means for impressing a marking signal on said outgoing path at predetermined intervals independently of whether said receiving relay responds to a corresponding marking signal.

36. In a telegraph signal repeating device, an incoming signaling path, an outgoing signaling path, a receiving relay associated with said incoming signaling path and adapted to cause received signals to be impressed on said outgoin path, and means for impressing a marking signal on said outgoing path in timed relation to signals received by said receiving relay but independently of Whether said receiving relay concurrently responds to a corresponding marking signal.

37. In a start-stop telegraph signal repeating device, an incoming signaling path, an outgoing signaling path, a receiving relay responsive to start-stop telegraph signals arriving on said incoming path and adapted to cause said signals to be impressed on said outgoing path, and means for impressing a stop signal on said outgoing path, a predetermined interval after a start signal whether or not said receiving relay receives a stop signal.

38. In a start-stop telegraph signal repeating device, an incoming signaling path, an outgoing signaling path, a receiving relay responsive to start-stop telegraph signals arriving over said incoming path and adapted to cause said signals to be impressed on said outgoing path, and means for impressing a stop signal on said outgoing path, a predetermined interval after response of said receiving relay to a start signal whether or not said receiving relay receives a stop signal to be repeated to said outgoing path.

GEORGE A. LOCKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,875,935 Sandeman et al. Sept. 6, 1932 2,022,051 Locke Nov. 26, 1935 2,339,536 Wendt Jan. 18, 1944 2,375,125 Martin May 1, 1945 

